Among the reasons the English writer Colin Thubron offers for dragging his sexagenarian body along 7,000 miles of the Silk Road is an urge to “understand something before it’s too late.” That goal, at once humble and ominous, is typical of the vision of travel embodied in “Shadow of the Silk Road” (HarperCollins, 344 pages, $25.95), a fascinating but uneven account of eight months spent on the network of trade routes by which ancient Rome and China exchanged goods, as well as ideas.

Politically fraught itineraries are Mr. Thubron’s specialty; earlier trips have taken him to the Middle East, Cyprus, and the Soviet Union, both before and after its dissolution. Mr. Thubron’s latest route snakes westward from Xian, China, through former Soviet republics, Afghanistan, and Iran, to Antioch, Turkey. Although he covered much of the same ground in the excellent “Behind the Wall” (1987) and “The Lost Heart of Asia” (1994), Mr. Thubron has taken the tensions caused by Islamist terrorism as a spur to revisit the Muslim territory at the pivot between East and West.

Mr. Thubron approaches others’ beliefs with curiosity and respect, though his own faith is “faded.” His set-piece descriptions of various mosques, shrines, and tombs are among the highlights of the book, particularly his account of the majestic mosque of Gawhar Shad in Mashhad, Iran, where, he notes not unpointedly, the “Muslim umma was assembled in peace.” Swept up in the crowd, he glimpses a “vista of mosaic tiles or a flash of gold” as he is borne into the inner courtyards, where he sees “a vast, hushed quadrangle across a sea of moving worshippers.” Unusually for a Westerner, he conveys a keen sense of the mosque’s significance as a site of active worship as well as an architectural treasure. Mr. Thubron, who also writes fiction, has a novelist’s empathetic feel for character. He falls in with shepherds as easily as with teachers. Tellingly, he refers to a truck in which he hitches a ride as “ours,” the choice of pronoun reflecting his ready identification with the driver. From casual conversations along the way, he spins evocative sketches of the locals that provide an organic sense of these societies in flux.

Reticence about himself underwrites Mr. Thubron’s interest in others. He travels in part to escape himself, savoring the “weightless, thinned” feeling produced by immersion in the foreign. Much of the little introspection he does include is channeled through the hokey device of conversations with an imaginary ancient trader who says things such as, “I’d rather trust a lame donkey.” Mr. Thubron’s main fear when traveling, he explains in one of their chats, is of “experiencing nothing,” because then “you hear only yourself.”

Mr. Thubron’s poetic prose conjures a world of strong colors and stark terrain, with “mountainflanks splashed tangerine or marble-white” and peaks that “erupted about us to eighteen thousand feet in sheets of inky rock.” But he writes with a seductive facility that sometimes leads him too far. Passing the night in a Kyrgyz yurt, he examines his surroundings by the glow of his flashlight: “Its crimson skeleton of willow boughs converged on the apex of its dome in a carnival blaze,” he recalls. “No surface escaped ornament.” Indeed.

His taste for stylization extends to a fondness for portentous abstraction: the inky mountains “made a fearful, somber violence;” a woman he meets “emitted a sad wildness;” and the Silk Road “spread variousness, and a rich impurity.” It’s as if Mr. Thubron prefers to paint with colors untempered by dilution. His description of an elderly woman whose “eyes glimmered in a landscape infinitely faded” suffers from a similar flaw. The flourish of “infinitely” feels unearned and rhetorical, blunting the impact of the image. Nor does the repetition of “infinitely” two paragraphs later help (“Even in my own veins the blood was infinitely more complex than I could know”).

Even so, there are many passages of finely turned description that draw on Mr. Thubron’s strengths. Near Xian, he visits the underground tomb of the emperor Qin Shi Huang, which is guarded by hundreds of life-size statues. Solemn but vivid, he evokes the uncanny sight of the ranks of terra-cotta warriors “once brilliant in vermilion and green” but now “faded to spectral beige” who “move through the earth in their hundreds, eleven columns deep.”

In Mr. Thubron’s depiction, the Silk Road provides a cautionary tale of mutual misunderstanding. Although tightly bound by trade, he emphasizes, Rome and China were deeply ignorant of each other. Goods made their way from one terminus to the other in “an endless, complicated relay race,” and so “no Romans strolled along the boulevards of Changan; no Chinese trader astonished the Palatine.” In the absence of direct contact, secondhand reports blossomed into myth. The Romans believed that silk came from a pacific kingdom free from crime, while the Chinese imagined a splendid city in the west governed by philosophers. The metaphoric lesson for the present is clear, but Mr. Thubron is pessimistic: On the Mediterranean shore, his journey complete, he sees that “to the west and east the sky was not the blue calm of my imagined homecoming, but a troubled cloudscape that swept the sea in moving gleams and shadows.”

Mr. Farrington, a member of the editorial staff of the New Yorker, last wrote for these pages on Alexander Waugh’s memoir “Fathers and Sons.”